<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!--内部js-->
    <Script>
        var number1= 3;
        var number2= 3.1;
        var number3= NaN;
        //输出到页面上
        document.write(number1+"<br>");//加一个换行
        document.write(number2+"<br>");
        document.write(number3+"<br>");
        var str = "abc";
        document.write(str+"<br>");
        var flag = true;
        document.write(flag+"<br>");
        var obj1= null;
        var obj2 = undefined;
        document.write(obj1+"<br>");
        document.write(obj2+"<br>")
    </Script>



</head>
<body>

</body>
</html>